1. Field of the Invention
This application relates to a light emitting diode (hereinafter called “LED”) module and a backlight assembly having the LED module.
2. Discussion of the Related Art
Among various display device representing image and/or video data, the liquid crystal display device (hereinafter called “LCD device”) becomes a representative display device because it has a lighter weight feature and a thin flat panel device feature due to the semiconductor technology. As the LED device is applied with inactive display panel which cannot emit light by itself, it is required to be equipped with backlight assembly for supplying light from the rear side of the display panel.
For the light source of backlight unit, the fluorescent lamp such as Cold Cathode Fluorescent Lamp (CCFL) has been used. Recently, however, the light emitting diode (hereinafter “LED”) starts to be applied because it has many merits in consumption electric power, weight, luminescence and so on. The LED backlight assembly can be made of single LED or a module comprising a plurality of LEDs.
A light-emitting diode, usually called an LED, is a semiconductor diode that emits incoherent narrow-spectrum light when electrically biased in the forward direction of the p-n junction, as in the common LED circuit. This effect is a form of electroluminescence. Like a normal diode, the LED consists of a chip of semiconducting material impregnated, or doped, with impurities to create a p-n junction. As in other diodes, current flows easily from the p-side, or anode, to the n-side, or cathode, but not in the reverse direction. Charge-carriers—electrons and holes—flow into the junction from electrodes with different voltages. When an electron meets a hole, it falls into a lower energy level, and releases energy in the form of a photon.
The wavelength of the light emitted, and therefore its color, depends on the band gap energy of the materials forming the p-n junction. The color of the emitted light depends on the composition and condition of the semiconducting material used, and can be infrared, visible, or ultraviolet. Therefore, using the band gap energy of the materials forming the p-n junction, it is possible to get various light colors, for example, blue, green or white.
As the LED has simple structure and low cost for mass-production, LED is applied to various industrial fields. Furthermore, as it is possible to form a thin film structure, it is used for backlight of the inactive display panels.
However, LED makes a lot of heat energy so that the heat energy can make bad effects, for example, shortening the life-time of LED or defects on LED itself.